Apparatus for casehardening glass plates



Jul 29, 1941. w OWEN 2,251,160

APPARATUS FOR CASEHARDENING GLASS PLATES Filed Oct. 14, 1938 3 Sheets-Sheet l INVENTOR. ML. L 1941 Ou/E N A TTORNEYS.

July 29, 1941. w. OWEN APPARATUS FOR CASEHARDENING GLASS PLATES Filed Oct. 14, 1938 3 Sheets-Sheet 2 INVENTOR. Oa/E/v v rV TORNEYS.

July 29, 1941. v w. OWEN APPARATUS FOR CASEHARDENING GLASS PLATES Filed Oct. 14, 1938 3 Sheets-Sheet 3 INVENTOR. M4. 1., 04M Ow EN TTORNEYS.

- Patented July .29, 1941 APPARATUS FOR CASEHABDENING GLASS PLATES William Owen, Pittsburgh, Pa., assignor to Pittsburgh Plate Glass Company, Allegheny County, Pa., a corporation of Pennsylvania Application October 14, 1938, Serial No. 234,988

7 Claims.

The invention relates to apparatus for case hardening glass sheets and is particularly adapted for use with thin glass although capable of use with sheets of any thickness. One of the objects of the invention-is the provision of a simple compact apparatus which will permit the treatment of the glass to case harden it without marring the surfaces and with a minimum of breakage. an apparatus which has a large capacity and whose use requires a of hand labor, the work of the single operator being restricted to the feeding of the sheets to the apparatus and the control of the motor which provides the step by step feed of the sheets through the heating and chilling zones. Certain embodiments of the invention are illustrated in the accompanying drawings, wherein: I

Figure 1 is a vertical section through an apparatus. Fig. 2 is a side elevation. Fig. 3 is a detail perspective view showing the method of supporting the glass sheets on the screens. Fig. 4 is a perspective view showing a modification. And Fig. 5 is a detail sectional view through one of the plates for supporting the glass sheets as employed in the Fig. 4 construction.

Referring to the drawings, 6, 6 are vertical I-beams constituting the framework of the ap-' paratus, such I-beams being anchored to the floor, as indicated at I in Fig. 1 and having their upper ends supported on the horizontal I-beams 8 carried by the superstructure of the-buildin in which the apparatus is housed.

Mounted on the beams 6, 6 is a vertical furnace 9 slotted at its upper and lower ends and provided with suitable heating means for bringing the temperature of the furnace to the desired point. Any suitable heating means may be employed, the one shown being electrical resistance elements I0 located in the walls of the furnace, such resistance elements being supplied with current from the terminals H and I2. Mounted beneath the furnace and in alinement therewith are the cooling means for chilling the glass sheets treated in the apparatus. This means comprises a'pair of headers l3, 13 having distributed over their front sides the outlet nozzles I4. These headers are supplied with air under pressurefrom the pipes l5, l5. Each header is supported at its ends upon a pair of eccentricslB, l6 carried by shafts I], ll, such shafts being mounted in suit-- A further object is the provision of sheets.

means of a chain l8a (Fig. 2) passing around sprockets 22 on the ends of the shafts. Means are thus provided for giving the headers an oscillatory movement, thus securing a better distribution of the air from the nozzles it over the glass The glass sheets to be treated are moved downward through the furnace and past the chilling means by means of a .pair of endless conveyor screens '23, 24 whose vertical flights move together through the furnace and past the chilling means, as illustrated in Fig. 1. The upper and lower ends of the furnace are slotted to permit the passage of these vertical flights and closure means are provided for the slots in the form of pairs of asbestos covered rollers 25 and 26 arranged so as to press lightly against the screens passing therebetween.

The endless screen 23 passes at its upper and lower ends around the drums 21 and 28, such drums being mounted on the shafts 29 and 30. The shaft 29 is carried by suitable bearings 3| secured rigidly to the sides of the beams or posts 6, 6, while the shaft 30 is carried by bearings 32 which are mounted slidably on the flanges of the posts 6, 6 so that the weight of the drum 28 and shaft 30 serves to tension the screen. The screen 23 passes at its upper and lower ends around the drums 33 and 36, the drum 33 being mounted upon a shaft 35 carried by fixed bearings 36 securedto the posts 6, while the drum 34 is mount.- ed upon a shaft 31 carried by bearings 38 slidable on the flanges of the I-beams 6 so that the screen is tensioned by the weight of the drum 34 and shaft 37. The drums 21 and 33 are driven from the motor 33 by means of the chain 40 passing around a sprocket on the shaft of the motor and over the sprockets 4| and 42 carried by the shafts 29 and 35 respectively. The upright contiguous flights of the conveyor screens are thus moved together or synchronously as a unit through the heating chamber of the furnace 3.

Theglass sheets 43, which are carried through the furnace and past the chilling means by the screens, are fed to the apparatus just above the drum 33 by the operator. Such sheets are supported against downward movement with respect to the screens during theirdownward travel by the means shown most. clearly in Fig. 3. Such means comprises a plate 44 of heat resisting metal provided with the teeth 45 and are attached to the screen 23 by means of suitable pins or bolts 46. The purpose of the teeth is to give a minimum of contact between the edge of, the glass sheet and the supporting plate, and a cush ioning effect is preferably provided for by the use of small bodies a of asbestos wool cemented to the teeth 45. The plate 44 is preferably slotted, as indicated at 46a to reduce any tendency to warp under the heat conditions encountered in the furnace. The plates 44 are distributed along the screen 23 at suitable intervals, as indicated in Fig. 1, so that while one sheet of glass is being heated in the furnace, the next sheet below is in position for cooling between the chilling devices. An arm 48a pivoted at 48b on the post 6 carries a roll 480 which serves to hold the glass sheet against the screen 23 until the lower edge of such sheet is closely adjacent the horizontal conveyor 41, later described.

In order to carry the glass sheets away as they reach the bottom of the screens 23 and 24, a horizontal conveyor is provided in the form of an endless belt 41 which extends laterally and passes around pulleys, such as 48, at the ends of the device, the conveyor being driven by suitable means which are not shown. The pulley 48 is mounted upon a shaft 49 which is carried by extensions projecting from the lower ends of the bearing members 32 so that the end of the conveyor 41 is maintained in fixed relation with respect to the lower end of the endless screen 23.

In operation, the adjacent vertical flights of the screens 23 and 24 are given a step by step movement downward through the furnace 9 and past the headers I3, l3 by starting and stopping the motor 39 at will. During the pause in each movement of the screens, a sheet of glass is heated to the softening point in the furnace 9 and at the same time the sheet of glass carried by the screens below it is chilled by the air blasts from the nozzles M. The movement of the screens to shift the heated plate to chilling position between nozzles is relatively fast so that the chilling of the glass sheet occurs very quickly after the heating step has been completed. The opposing flights of the screens 23 and 24 press upon opposing surfaces of the glass sheets as they pass through the furnace and past the chillin means so that such faces are maintained in true vertical planes during the treatment. Due to this support by the screens during the chilling operation, there is no tendency of the air pres- 'sure from the nozzles to deform the sheet, even though such sheet be of relatively thin glass. It is thus possible to case harden thinner sheets of glass than is the case in operations heretofore practiced wherein the only support of the glass sheet is from its upper edge, the weight of the sheet being depended upon in such case to hold it flat. The screen employed may be of widely varying mesh and construction, but is in all cases relatively light in weight and is preferably of heat resisting material, such as nickel chromium.

Figs. 4 and 5 illustrate a modification which differs from that of Figs. 1 to 3 only in the character of the supporting screen. In this case the s pporting screen consists entirely of vertical strands 50 which are suitably spaced and pass around drums at their upper and lower edges as in the construction heretofore described, only the upper drums 5| and 52 being shown. The spacing of the wires 50 is maintained by means of the transverse plates 53, 53 of heat resisting metal, such as stainless steel, which are welded to the wires. These plates 53, 53 act as the supports for the glass sheets and are similar in construction to the plates 44 heretofore described in connection with the apparatus of Figs. 1 to 3. In order to give the wires driving traction with respect to the drums over which they pass, the plates 53 are preferably provided on their rear sides with the spikes 54 shown in Fig. 5. The drums in all types of construction are preferably covered with asbestos fabric so that the spikes 54 penetratethe material and provide the necessary driving contact. The wires 50 in conjunction with the cross members 53 constitute in effect a coarse screen, and it will be understood that the term screen as used in defining the invention is of relatively broad scope.

What I claim is:

'1. In an apparatus for case hardening a glass sheet, endless conveyor screens having upright flights disposed in substantially parallel contiguous relation for engaging opposite sides of the glass sheet, means connected to the screens for driving them synchronously, means for supporting the glass sheet between said flights, heating means receiving said flights for travel therethrough, air blast directing means on opposite sides of the flights for directing chilling air blasts through said flights from opposite directions after they have passed through the heating means, and means for supporting said heating means and .said air blast directing means in juxtaposed relation.

2. In an apparatus for case hardening a glass sheet, endless conveyor screens having upright flights disposed in substantially parallel contiguous relation for engaging opposite sides of the glass sheet, means connected to the screens for driving them synchronously, means for supporting the glass sheet-between said flights, heating means receiving said flights for travel therethrough, air blast directing means on opposite sides of the flights for directing chilling air blasts through said flights from opposite directions after they have passed through the heating means, means for supporting said heating means and said air blast directing means in juxtaposed relation, and discharging means disposed in coacting relation with said flights for feeding the glass sheet therefrom to a glass transporting means.

3. In an apparatus for case hardening a glass sheet, endless conveyor screens having upright flights disposed in substantially parallel contiguous relation for engaging opposite sides of the glass sheet, means connected to the screens for driving them synchronously, one of said screens having supporting means upon which the glass sheet rests as it is held in an upright position between said flights, heating means receiving said flights for travel therethrough, air blast directing means on opposite sides of the flights for directing chilling air blasts through said flights from opposite directions after they have passed through the heating means, and means for supporting said heating means and said air blast directing means in juxtaposed relation.

4. In an apparatus for case hardening glass sheets, heating means for reducing the glass sheets to softening temperature, sets of air blast directing means disposed in opposed relation at horizontally spaced locations and in juxtaposed relation to the heating means, endless conveyor screens having uprightsubstantially parallel contiguous flights passing through the heating means and between the sets of air blast directing means,

one of said screens having thereon spaced elements to determine the position of the glass sheets in spaced relation according to the spacing between the heating means and the air blast directing means whereby when one glass sheet is sheets to softening temperature, sets 01' air blast V directing means disposed in opposed relation at horizontally spaced locations and in juxtaposed relation to the heating means, endless conveyor screens having upright substantially parallel contiguous flights ,passing through th heating means and between the sets of air blast directing means, transverse groups of glass supporting pointed elementsspaced longitudinally upon said 1 screens to determine the position of the glass v sheets in spaced relation according to the spacing between the heating means and the air blast directing means whereby when one glass sheet is disposed in the heating means, the next adjacent contiguous relation for engaging oppositesides of.

the glass sheet, drums receiving the upper extremities of the conveyor screens and carrying the latter in vertically suspended relation, means for rotatably supporting the drums horizontally, means connected tothe' drums to drive them synchronously, a floating drum suspended in the lower extremity of each endless screen and constituting a tensioning weight for such screen,

means including vertically slidable bearing supports rotatably connected to each lower-floating drum, heating means receiving said upright flights for travel therethrough, air blast directing means on opposite sides of the flights for directing chilling air blasts through said flights from opposite directions after they have passed through the heating means, and means for supporting said heating means and said air blast directing means in juxtaposed relation.

7. In an apparatus for case hardening a glass sheet, upright endless conveyor screens having upright flights, disposed in substantially parallel contiguous relation for engaging opposite sides of the glass sheet, drums receiving the upper extremities of the conveyor screens and carrying the latter in vertically suspended relation, means for rotatably supporting the drums horizontally, one of said drums having its axislspaced vertically from the axis of the other drum, means connected to the drums to drive them synchronously, a rotatably supported drum receiving the lower extremity of each endless screen, heating means receiving said upright flights for travel therethrough, air blast directing means on opposites'ides of-theflights for directing chilling air blasts through said flights from opposite directions after they have passed through the heating 'means, and means for suppbrting said heating means and said air blast directing means in juxtaposed relation.

, WILLIAM OWEN. 

